Yes that is absolutely useless and was a bane in my side for so long. This needs to be fixed, though to be honest I kept forgetting to report it.
What you need to do is open a CMD shell in windows and manually run the same command it is running, the second line there. When you do you will see you have some preprocessor error, like a bad UPROPERTY or something that is causing that initial step to fail, but UBT doesn’t report it back to VS.
EDIT: Based on your edit I can tell you the problem is oyu can’t make an “int” into a Blueprintable property. It needs to be int32. In fact you should never us plain int anywhere in Unreal.
on the same VS console you have an “output flap”. It can’t be seen on your screenshoot, but it is at bottom left. There sometimes you have a better error description.
Specifically, “Do not use the C++ int type in portable code, since it is dependent on the compiler how large it is.”
As for Intellisense errors, pretty much just ignore them. Intellisense sucks and is so far behind changes it is practically useless. Further more, it will often lag behind stuff in your headers, because that stuff needs to be preprocessed by UBT first.